A functional model of the mammalian circadian pacemaker.

This paper describes a general model of the mammalian circadian pacemaker with specific parameters for golden hamsters. The model successfully simulates free-runs in constant darkness and constant light, phase shifts induced by light pulses and entrainment and relative coordination under light-dark cycles. It also accounts for the recent findings that the amplitude of the phase response curve to light pulses is dependent on the free-running period of the animal and on the previous history of photic stimulation. Effects of non-photic stimuli on the circadian pacemaker are discussed.